Hide properties of intermediate objects and remove data class attributes

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/convert.kt

@@ -91,11 +91,13 @@ public inline fun <T, C, reified R> Convert<T, C?>.notNull(
     }
 
 @HasSchema(schemaArg = 0)
-public data class Convert<T, out C>(val df: DataFrame<T>, val columns: ColumnsSelector<T, C>) {
+public class Convert<T, out C>(internal val df: DataFrame<T>, internal val columns: ColumnsSelector<T, C>) {
     public fun <R> cast(): Convert<T, R> = Convert(df, columns as ColumnsSelector<T, R>)
 
     @Interpretable("To0")
     public inline fun <reified D> to(): DataFrame<T> = to(typeOf<D>())
+
+    override fun toString(): String = "Convert(df=$df, columns=$columns)"
 }
 
 public fun <T> Convert<T, *>.to(type: KType): DataFrame<T> = to { it.convertTo(type) }

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/format.kt

@@ -42,7 +42,8 @@ public fun <T, C> FormatClause<T, C>.perRowCol(formatter: RowColFormatter<T, C>)
 public fun <T, C> FormatClause<T, C>.with(formatter: CellFormatter<C>): FormattedFrame<T> =
     formatImpl { row, col -> formatter(row[col]) }
 
-public fun <T, C> FormatClause<T, C>.where(filter: RowValueFilter<T, C>): FormatClause<T, C> = copy(filter = filter)
+public fun <T, C> FormatClause<T, C>.where(filter: RowValueFilter<T, C>): FormatClause<T, C> =
+    FormatClause(filter = filter, df = df, columns = columns, oldFormatter = oldFormatter)
 
 public fun <T> FormattedFrame<T>.format(): FormatClause<T, Any?> = FormatClause(df, null, formatter)
 
@@ -129,12 +130,15 @@ public class FormattedFrame<T>(internal val df: DataFrame<T>, internal val forma
         configuration.copy(cellFormatter = formatter as RowColFormatter<*, *>?)
 }
 
-public data class FormatClause<T, C>(
-    val df: DataFrame<T>,
-    val columns: ColumnsSelector<T, C>? = null,
-    val oldFormatter: RowColFormatter<T, C>? = null,
-    val filter: RowValueFilter<T, C> = { true },
-)
+public class FormatClause<T, C>(
+    internal val df: DataFrame<T>,
+    internal val columns: ColumnsSelector<T, C>? = null,
+    internal val oldFormatter: RowColFormatter<T, C>? = null,
+    internal val filter: RowValueFilter<T, C> = { true },
+) {
+    override fun toString(): String =
+        "FormatClause(df=$df, columns=$columns, oldFormatter=$oldFormatter, filter=$filter)"
+}
 
 public fun <T, C> FormattedFrame<T>.format(columns: ColumnsSelector<T, C>): FormatClause<T, C> =
     FormatClause(df, columns, formatter)

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/group.kt

@@ -28,7 +28,9 @@ public fun <T> DataFrame<T>.group(vararg columns: KProperty<*>): GroupClause<T,
 
 // region GroupClause
 
-public data class GroupClause<T, C>(val df: DataFrame<T>, val columns: ColumnsSelector<T, C>)
+public class GroupClause<T, C>(internal val df: DataFrame<T>, internal val columns: ColumnsSelector<T, C>) {
+    override fun toString(): String = "GroupClause(df=$df, columns=$columns)"
+}
 
 // region into
 

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/groupBy.kt

@@ -104,9 +104,11 @@ internal fun <T, G> GroupBy<T, G>.internal(): GroupByImpl<T, G> = this as GroupB
 
 public interface Grouped<out T> : Aggregatable<T>
 
-public data class ReducedGroupBy<T, G>(
+public class ReducedGroupBy<T, G>(
     @PublishedApi internal val groupBy: GroupBy<T, G>,
     @PublishedApi internal val reducer: Selector<DataFrame<G>, DataRow<G>?>,
-)
+) {
+    override fun toString(): String = "ReducedGroupBy(groupBy=$groupBy, reducer=$reducer)"
+}
 
 internal fun <T, G> GroupBy<T, G>.reduce(reducer: Selector<DataFrame<G>, DataRow<G>?>) = ReducedGroupBy(this, reducer)

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/insert.kt

@@ -43,7 +43,9 @@ public inline fun <T, reified R> DataFrame<T>.insert(
 
 // endregion
 
-public data class InsertClause<T>(val df: DataFrame<T>, val column: AnyCol)
+public class InsertClause<T>(internal val df: DataFrame<T>, internal val column: AnyCol) {
+    override fun toString(): String = "InsertClause(df=$df, column=$column)"
+}
 
 // region under
 

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/move.kt

@@ -150,6 +150,8 @@ public fun <T, C> MoveClause<T, C>.toLeft(): DataFrame<T> = to(0)
 
 public fun <T, C> MoveClause<T, C>.toRight(): DataFrame<T> = to(df.ncol)
 
-public class MoveClause<T, C>(internal val df: DataFrame<T>, internal val columns: ColumnsSelector<T, C>)
+public class MoveClause<T, C>(internal val df: DataFrame<T>, internal val columns: ColumnsSelector<T, C>) {
+    override fun toString(): String = "MoveClause(df=$df, columns=$columns)"
+}
 
 // endregion

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/pivot.kt

@@ -212,10 +212,12 @@ public interface Pivot<T> : Aggregatable<T>
 
 public typealias PivotColumnsSelector<T, C> = Selector<PivotDsl<T>, ColumnsResolver<C>>
 
-public data class ReducedPivot<T>(
+public class ReducedPivot<T>(
     @PublishedApi internal val pivot: Pivot<T>,
     @PublishedApi internal val reducer: Selector<DataFrame<T>, DataRow<T>?>,
-)
+) {
+    override fun toString(): String = "ReducedPivot(pivot=$pivot, reducer=$reducer)"
+}
 
 internal fun <T> Pivot<T>.reduce(reducer: Selector<DataFrame<T>, DataRow<T>?>) = ReducedPivot(this, reducer)
 
@@ -230,10 +232,12 @@ public interface PivotGroupBy<out T> : Aggregatable<T> {
     public fun default(value: Any?): PivotGroupBy<T>
 }
 
-public data class ReducedPivotGroupBy<T>(
+public class ReducedPivotGroupBy<T>(
     @PublishedApi internal val pivot: PivotGroupBy<T>,
     @PublishedApi internal val reducer: Selector<DataFrame<T>, DataRow<T>?>,
-)
+) {
+    override fun toString(): String = "ReducedPivotGroupBy(pivot=$pivot, reducer=$reducer)"
+}
 
 @PublishedApi
 internal fun <T> PivotGroupBy<T>.reduce(reducer: Selector<DataFrame<T>, DataRow<T>?>): ReducedPivotGroupBy<T> =

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/rename.kt

@@ -45,7 +45,9 @@ public fun <T, C> DataFrame<T>.rename(vararg cols: KProperty<C>): RenameClause<T
 public fun <T> DataFrame<T>.rename(vararg cols: String): RenameClause<T, Any?> = rename { cols.toColumnSet() }
 
 @HasSchema(schemaArg = 0)
-public data class RenameClause<T, C>(val df: DataFrame<T>, val columns: ColumnsSelector<T, C>)
+public class RenameClause<T, C>(internal val df: DataFrame<T>, internal val columns: ColumnsSelector<T, C>) {
+    override fun toString(): String = "RenameClause(df=$df, columns=$columns)"
+}
 
 /**
  * ## Rename to camelCase

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/replace.kt

@@ -33,7 +33,9 @@ public fun <T> DataFrame<T>.replaceAll(
     return update(columns).with { map[it] ?: it }
 }
 
-public data class ReplaceClause<T, C>(val df: DataFrame<T>, val columns: ColumnsSelector<T, C>)
+public class ReplaceClause<T, C>(internal val df: DataFrame<T>, internal val columns: ColumnsSelector<T, C>) {
+    override fun toString(): String = "ReplaceClause(df=$df, columns=$columns)"
+}
 
 public fun <T, C> ReplaceClause<T, C>.with(vararg columns: AnyCol): DataFrame<T> = with(columns.toList())
 

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/split.kt

@@ -28,8 +28,10 @@ public fun <T, C> DataFrame<T>.split(vararg columns: ColumnReference<C?>): Split
 
 public fun <T, C> DataFrame<T>.split(vararg columns: KProperty<C?>): Split<T, C> = split { columns.toColumnSet() }
 
-public data class Split<T, C>(internal val df: DataFrame<T>, internal val columns: ColumnsSelector<T, C?>) {
+public class Split<T, C>(internal val df: DataFrame<T>, internal val columns: ColumnsSelector<T, C?>) {
     public fun <P> cast(): Split<T, P> = this as Split<T, P>
+
+    override fun toString(): String = "Split(df=$df, columns=$columns)"
 }
 
 public data class SplitWithTransform<T, C, R>(

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/update.kt

@@ -40,14 +40,16 @@ import kotlin.reflect.KProperty
  *
  * For more information: {@include [DocumentationUrls.Update]}
  */
-public data class Update<T, C>(
-    val df: DataFrame<T>,
-    val filter: RowValueFilter<T, C>?,
-    val columns: ColumnsSelector<T, C>,
+public class Update<T, C>(
+    internal val df: DataFrame<T>,
+    internal val filter: RowValueFilter<T, C>?,
+    internal val columns: ColumnsSelector<T, C>,
 ) {
     public fun <R : C> cast(): Update<T, R> =
         Update(df, filter as RowValueFilter<T, R>?, columns as ColumnsSelector<T, R>)
 
+    override fun toString(): String = "Update(df=$df, filter=$filter, columns=$columns)"
+
     /*
      * This argument providing the (clickable) name of the update-like function.
      * Note: If clickable, make sure to [alias][your type].
@@ -188,7 +190,7 @@ public fun <T, C> DataFrame<T>.update(vararg columns: ColumnReference<C>): Updat
  * @param [predicate] The [row value filter][RowValueFilter] to select the rows to update.
  */
 public fun <T, C> Update<T, C>.where(predicate: RowValueFilter<T, C>): Update<T, C> =
-    copy(filter = filter and predicate)
+    Update(df = df, filter = filter and predicate, columns = columns)
 
 /** ## At
  * Only update the columns at certain given [row indices][CommonUpdateAtFunctionDoc.RowIndicesParam]: